1. Description of the Prior Art
The advancement of webs of material with a constant motion is found in several patents and apparatus in which alternate gripping and advancement are used is well known. In particular, applicant's U.S. Pat. No. 3,733,773 as issued May 22, 1973 is noted. In this and other showings the film or films are alternately gripped to advance the film or films. In this and other known apparatus, patented and unpatented, the film and/or films are gripped and the advance may be with a constant motion. The cams used in prior art devices may provide an overlap in the film advancing apparatus as is provided in the present invention. The crank arm moves the connected oblong array of roller chain so as to produce a continuous motion and constant velocity. The shortening or lengthening of the crank arm changes each gripper actuation and overlap in accordance with said length of crank arm.
In the course of a prior art search, in addition to U.S. Pat. No. 3,733,773 above noted, there was found U.S. Pat. No. 1,537,749 to COLGROVE as issued May 12, 1925 and showing alternate gripping means and alternate actuation of levers. The Pitman arm motion of COLGROVE does not produce a constant speed. Alternate gripping is shown in U.S. Pat. No. 2,107,607 as issued to GOBEL on Feb. 8, 1938. U.S. Pat. No. 3,403,831 to LAWSON, Jr., et al as issued Oct. 1, 1968 shows a gripping device with a Pitman arm drive and timed gripping. U.S. Pat. No. 3,583,268 to SCRIBNER as issued June 8, 1971 shows two gripping head systems but the drive system does not provide the constant velocity of the present invention. U.S. Pat. No. 3,844,152 to PEYTAVIN as issued Oct. 29, 1974 also shows a Pitman drive and gripping means but the film advance mechanism of this patent is produced by cam means and adjustment of the length of delivered film is not shown. The present invention utilizing an oblong path of the roller chain and a reciprocated frame therewith produces a determined overlap of gripper actuation so that the film is advanced with a positive and sequential gripping.
The packaging of small items and/or the forming of pouches is substantially dependent on the constant advancement of the film web or webs. Blister packages in which small items such as pills or the like are deposited and sealed in formed packets of film are well known. These items may be individually packaged or may be used with a lamination or foil and/or the like particularly where sealing is required and desired. The carriers of the grippers usually also carry the work stations for shaping and sealing the film or films. Conventionally the film or films are shaped into receiving pockets and a product placed therein after which the product is sealed by heat or an application of adhesive. Usually in performing the operations of making a package and the final sealing there are several successive work stations in which one or more sheets are fed. Usually this web is in roll form and is advanced by a continuous moving means.
The prior art shows squeeze rollers rotated by variable speed motors which are often deficient as to accuracy and speed. Slipage and/or skewing of the web may also occur. The invention to be hereinafter more fully described grips the traveling web of film and advances it forwardly at a determined constant velocity. A change of pivot support for the vertical levers advances the film with a more-or-less distance and a mark or indicating means may be placed on the web and this adjustment used to bring the web into coincidence. The crank arms are lengthened or shortened to change the overlap of the grippers on the advancing film.
In the apparatus to be hereinafter more fully described, the roller chain travels in an oblong manner to move connected drag links at a determined rate. These drag links are moved by the roller chain, each of which are moved by a sprocket to provide the constant velocity and continuous motion. The roller chain assemblies are carried on and by a movable frame which is moved by crank arms with a predictable overlap. The pivoted lever arms have their pivot shifted to lengthen or shorten the advancement of the film. The apparatus of this invention provides an inexpensive and adjustable means for advancing, in a constant velocity and continuous motion, one or more webs of film.
2. Summary of the Invention
This invention may be summarized, at least in part, with reference to its objects. It is an object of this invention to provide, and it does provide, an apparatus producing a continuous motion and with a constant velocity for advancing a web of film. The advance of this film employs two gripper means, preferably one on each side of the advanced web and with the gripping actuation occurring only during a forward motion. The sliding arm on the distal end carries the actuated gripper and the Pitman arm moves an endless chain apparatus frame so that at one extent of travel the gripping end is moved forwardly with a combined actuation and when released is returned at a greater speed. Two such apparatus are employed to provide this complete and continuous advancement of the web.
It is a further object of this invention to provide, and it does provide, a film advancing apparatus in which the grippers are each carried by sliding members moved by crank arms and connected Pitman arms which move a frame on which is carried an endless roller chain drive disposed in an oblong array. The chain is moved by a driven sprocket and the chain is operatively connected to an arm which moves the gripper means.
It is still a further object of this invention to provide, and it does provide, apparatus that includes automatically actuated gripper devices that are disposed on opposite sides of the traveling web. These grippers are alternately actuated to engage and release the web of film and during the engaging time cycle the grippers are moved forward and retracted in response to lever arm movement created by drag links moved by roller chain assemblies disposed and traveling in an oblong continuous path. These chains are driven by sprockets which are driven by motor means. The roller chain is carried by a frame that is cycled back and forth by a pitman arm driven or moved by a crank arm. The crank arm throw is made more-or-less so that the movement of the Pitman arm increases or decreases the overlap in the gripper actuation. The crank arms, the Pitman arms, the roller chain assemblies, the cycled frames, the drag links, the lever arms and the sliding arms with their gripper means are at least two in number with the pivot support of the lever arms changed to increase or decrease the advance of the film web produced with each and every forward stroke of the sliding arm. The lever arms and the roller chain drives are two in number and are cycled alternately by a crank arm having a selected throw that is increased or decreased as desired to control the advance of the film web.
In brief, this apparatus providing the continuous motion and constant velocity to a web and/or web of film includes a motor means that powers a driven shaft secured in place as far as the machine is concerned. This driven shaft carries and rotates two sprockets that are positioned and disposed to drive two roller chain assemblies in an endless oblong path. The two roller chain assemblies are one hundred eighty degrees out-of-phase with each other. These roller chain assemblies each are operatively connected to a drag link member. This roller chain assembly is carried on a frame that is slidably mounted to be cycled back and forth by a crank arm connected to a Pitman arm that is pivotally connected to the cycled frame.
In the preferred embodiment there are two roller chains for each cycled frame making a total of four roller chains and two frames. The crank arms driving these frames are depicted as having adjusting means or slots for increasing or decreasing the throw of said arms. These slots are shown for increasing or decreasing the movement of the Pitman arm and the frame for the chain which merely decreases or increases the amount of overlap of the gripper on the film. There is additionally provided means for changing the positioning of the web so the web can be exactly matched with an indicator spot on the web. The pivot for the lever arms is shifted to increase or decrease the advancement of the web. The movable frame carrying the roller chain drive and the chains thereon in an oblong path provides a lengthened advancing stroke with the forward motion of the roller chain frame and a diminished return stroke with the return of the chain and frame. The overlap provided as the drag link is moved by the oblong chain and the Pitman arms is increased or decreased according to the desires of the particular operation being performed. An increase or decrease in the diameter of the supporting rollers of the oblong chain is also a factor in determining the overlap of the grippers. What is provided in this apparatus is a long forward stroke of the upper extent of the chain and forward movement of the frame and a foreshortened return stroke utilizing the arcuate travel of the chain around the pulleys and the return extent of the chain. The movement of the chain frame by the Pitman arm provides such an overlapping motion so the forward movement of the chain provides more than one-half of the roller chain extent on the forward stroke and the return stroke is equivalent to less than one-half of the roller chain extent.
In addition to the above summary the following disclosure is detailed in insure adequacy and aid in understanding of the invention. This disclosure, however, is not intended to cover each new inventive concept no matter how it may later be disguised by variations in form or additions of further improvements. For this reason there has been chosen a specific embodiment of continuous motion, constant velocity, film advancing apparatus as adopted for use with film webs and packaging by said films and showing a preferred means for constructing and utilizing said apparatus.